Serious Scarcity Substitution Instrument for isosorbide mononitrate tablets

23 Sep 2021

GPs should be aware that the Therapeutic Goods Administration (TGA) has been notified of shortages of Imdur Durules and Monodur Durules isosorbide mononitrate 120 mg modified release tablets.

The shortages are expected to continue until 19 December 2022. 

The TGA has made a Serious Scarcity Substitution Instrument (SSSI) to assist patients to access their medicine from their pharmacist without delay, ensure treatment is not interrupted and relieve workload pressure on prescribers and pharmacists. The SSSI: 

  • Declares registered medicines that contain 120 mg of isosorbide mononitrate that are modified release tablets as scarce medicines; and 

  • Specifies registered medicines that contain 60 mg of isosorbide mononitrate that are modified release tablets as substitutable medicines that pharmacists are permitted to dispense in substitution for the scarce medicines and specify the circumstances in which that substitution is permitted. 

The SSSI is in force from 18 September 2021 until 19 December 2022.  

Prescribers should be alert to the shortage of isosorbide mononitrate 120 mg modified release tablets when prescribing to your patients. 

The PBS listing for isosorbide mononitrate 60 mg modified release tablets provides a maximum quantity of 30 tablets, intended as monthly supply. You may need to contact Services Australia to request increased maximum quantity, so the PBS script is valid. 

More information is available from the TGA here.